Skirting between different levels of floor

[Harry Bloomfield]

Like this?

No - three pieces. A full height on the left, a full height on the right, then a triangular part in the middle just where the threshold strip is, so it leads down at 45 from one level to the other. You would need to make up a cardboard template, to get the angles.

Another way would be to add a plain, straight bit of wood, the same width as the the threshold strip and rising vertically up the wall, a bit thicker than the skirting and use that as your skirting height transition. This sort of idea ¬||_

 

[Curryracer]

I would prefer not to have any angles other than horizontal (ish) skirting or vertical walls. Your second suggestion is like this, but on the flat wall, with different height skirting either side:
The centre post the same width as threshold bar, but same as skirting colour.

 

[Harry Bloomfield]

The centre post the same width as threshold bar, but same as skirting colour.

Yes, that's what i had in mind for where the levels need to change.